Sprinklers employing drop down deflector assemblies are well-known. See U.S. Pat. Nos. 4,217,960 and 4,014,388. U.S. Pat. No. 4,217,960 discloses a concealed type sprinkler having a slotted cylindrical frame 7 threaded on a body 1. A deflector 14 is mounted on guide pins 12 which extend through bores in the frame bottom wall. A valve assembly 10 is secured to the deflector and loaded by a lever mechanism between the body outlet and frame bottom wall. The frame bottom wall is provided with a central opening through which the valve assembly can drop with the deflector. U.S. Pat. No. 4,014,388 discloses a concealed type sprinkler having a spring urged drop down deflector 17 whose guide pins 15, 16 extend through bores in frame arms 5, 6. The frame arms are part of a yoke frame integral with a body 1 and are loaded by a thermal element 8 between the body outlet and a compression screw 24.
U.S. Pat. No. 2,558,450 discloses a concealed type sprinkler having a yoke (26, 27) shaped as a tuning fork with an arm 62 bridging the yoke bight. Arm 62 is provided with a compression screw 49 and is mounted on the yoke at grooves 65 or on balls 71.
U.S. Pat. Nos. 4,596,289, 4,105,076, 4,015,665, 3,756,321 and 3,633,676 also disclose drop down deflectors. In these patents, the deflector is mounted on a pair of guide pins along the flange portion of a sprinkler body. U.S. Pat. No. 4,596,289 discloses a drop down valve 32 and deflector 22 mounted on guide pins 40, 42 along a sprinkler body flange 24. The flange can be separately manufactured and secured to the sprinkler body 12. U.S. Pat. No. 4,105,076 discloses a drop down valve 5 and deflector 12 mounted on guide pins 14 along a sprinkler body 16. U.S. Pat. No. 4,015,665 shows the same drop down valve and deflector construction as in U.S. Pat. No. 4,105,076. U.S. Pat. No. 3,756,321 discloses a drop down deflector 33 mounted on guide pins 31 along a sprinkler body flange 22. U.S. Pat. No. 3,633,676 discloses a drop down deflector 34 mounted on guide pins 29 along a sprinkler body flange.
U.S. Pat. Nos. 4,766,961 and 4,618,002 also disclose drop down deflectors mounted on guide pins along a sprinkler body flange U.S. Pat. No. 4,766,961 discloses a drop down valve 13 and a deflector 16 mounted on guide pins 17 along a sprinkler body flange 19. U.S. Pat. No. 4,618,002 discloses a drop down valve 30 and deflector 36 mounted on guide pins 38 along a sprinkler body flange 12.
Various sprinkler valve lever mechanisms are also well-known. For example U.K. patent No. 313 discloses a triple compound lever arrangement wherein a link g and lever h are fulcrumed along an annular shoulder in the sprinkler housing. Apparently, the lever is pivoted by the advance of an adjustment screw 1. U.K. patent No. 20,421 discloses a double compound lever arrangement wherein an upper lever f is pivotably mounted on a lip b, of a sprinkler cover, a lower lever g is pivotably mounted on the same lip b', the other end of the lever f is fulcrumed on the lever g, and the lever g is supported at its other end on a washer i coupled to a soldered tube arrangement k, 1 outside the sprinkler body. U.K. patent No. 343,806 discloses the general concept of a pair of fulcrum arms a, b captured by a clamp e. The arms hold a sprinkler bulb d in compression. Canadian patent No. 648,027 discloses a pair of lever arms 20 which: retain a valve cover plate 16 in position while holding a bulb 22 in compression. The lever arms are fulcrumed in the cover plate. U.K. patent No. 1,359,857 discloses a control valve for an open sprinkler head. A valve plug 24 is pre-loaded by a pivotable strut and a cam 30. A glass bulb 38 is pre-loaded between strut 35 and opposing (pivotable) strut 36. Strut 35 is pivotable about a notch 34 in a housing arm 28. Strut 36 is pivotable about a screw 41 in a housing 29. U.K. patent No. 347,984 discloses a bulb h pre-loaded between arms a1, b1 of a balanced pair of levers a, b. U.S. Pat. No. 3,195,647 discloses a pair of levers 40 which hold a fusible link 38 in tension while maintaining a valve 22 sealed against a sprinkler valve seat. The amount of tension exerted on the fusible link is set by deforming a portion of the sprinkler frame by a ran 50.
The present invention provides a solution to the problem of providing for adjustable compressive pre-load of a valve in a sprinkler utilizing a. rigid thermal responsive element, such as a frangible glass bulb, without loading the frame arms. As a result, the frame arms may be made lighter or of less bulk without affecting sprinkler operation.